/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.db.wal.checkpoint;

import org.apache.iotdb.db.utils.SerializedSize;

import java.io.DataInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

/**
 * Checkpoint is the basic element of .checkpoint file, including type, number of memTables, and
 * brief information of each memTable.
 */
public class Checkpoint implements SerializedSize {
    /**
     * checkpoint type 1 byte, checkpoint number 4 bytes
     */
    private static final int FIXED_SERIALIZED_SIZE = Byte.BYTES + Integer.BYTES;

    /**
     * checkpoint type
     */
    private final CheckpointType type;
    /**
     * memTable information
     */
    private final List<MemTableInfo> memTableInfos;

    public Checkpoint(CheckpointType type, List<MemTableInfo> memTableInfos) {
        this.type = type;
        this.memTableInfos = memTableInfos;
    }

    @Override
    public int serializedSize() {
        int size = FIXED_SERIALIZED_SIZE;
        for (MemTableInfo memTableInfo : memTableInfos) {
            size += memTableInfo.serializedSize();
        }
        return size;
    }

    public void serialize(ByteBuffer buffer) {
        buffer.put(type.getCode());
        buffer.putInt(memTableInfos.size());
        for (MemTableInfo memTableInfo : memTableInfos) {
            memTableInfo.serialize(buffer);
        }
    }

    public static Checkpoint deserialize(DataInputStream stream) throws IOException {
        byte typeNum = stream.readByte();
        CheckpointType type = CheckpointType.valueOf(typeNum);
        if (type == null) {
            throw new IOException("unrecognized checkpoint type " + typeNum);
        }
        int cnt = stream.readInt();
        List<MemTableInfo> memTableInfos = new ArrayList<>(cnt);
        for (int i = 0; i < cnt; ++i) {
            MemTableInfo memTableInfo = MemTableInfo.deserialize(stream);
            memTableInfos.add(memTableInfo);
        }
        return new Checkpoint(type, memTableInfos);
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (!(obj instanceof Checkpoint)) {
            return false;
        }
        Checkpoint other = (Checkpoint) obj;
        return this.type == other.type && Objects.equals(this.memTableInfos, other.memTableInfos);
    }

    public CheckpointType getType() {
        return type;
    }

    public List<MemTableInfo> getMemTableInfos() {
        return memTableInfos;
    }
}
